Kitchen Mixer Tap Fastening Query

[Mystarch]

Very new here and wanted a bit of advice if possible.

I'm trying to install a new Kitchen Mixer Tap, however cant seem to get the fastener off the old existing one. Pictures attached. the area available to work in is very restrictive and limited. Cant even get a wrench in as its quite a tight squeeze. Wondered if anyone can offer some advice or tools to help loosen this fastener to the kitchen tap.

Regards
A frustrated one

 

[polesapart]

One of these may help: https://www.screwfix.com/p/adjustable-basin-wrench-13mm-40mm/868xr

FWIW installer will have fixed tap to sink before fixing sink to worktop.

 

[Stuckinarut]

Looks like it’s only hand tight. Gap in the cupboard at the top and feed tool through? Grip plastic nut with one hand and turn the top of the tap with the other?

 

[Mystarch]

One of these may help: https://www.screwfix.com/p/adjustable-basin-wrench-13mm-40mm/868xr

FWIW installer will have fixed tap to sink before fixing sink to worktop.

Cheers. Was thinking of that too. But unsure whether it will catch the hand grip on the fastener. Worth a shot anyways.

 

[Mystarch]

Looks like it’s only hand tight. Gap in the cupboard at the top and feed tool through? Grip plastic nut with one hand and turn the top of the tap with the other?

Tried with a small wrench. It's really tight and barely has any room to twist.

Supposedly it's hand grip but it's really tight. Suppose it's been tightened with tool. The water softener piping in front doesn't help to give any room to exert force when twisting.